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ENERGIX-Stort program energi

Classification of lithium-ion cells for safe reuse

Alternative title: Klassifisering av litium-ion-celler for sikker gjenbruk

Awarded: NOK 13.5 mill.

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Project Period:

2022 - 2024

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Energy storage plays a key role towards a carbon-neutral economy in Europe by providing flexibility to the increasing share of intermittent and renewable energy sources. Batteries from electric vehicles are generally discarded when they no longer can contain more than 70-80% of their original maximum capacity. Due to the way EV battery packs are constructed, a single cell out of hundreds or thousands of cells in a pack can often be the culprit for this decrease in capacity. It is neither environmentally nor economically sound to scrap and recycle entire battery packs based on perhaps only a single cell in a pack being faulty. A better alternative is to classify all of the cells in the pack. In that way, poorly performing cells can be sent to recycling, while cells that still perform well can be used in second-life applications such as stationary energy storage. Together with battery experts at IFE, this project aims to develop methods and a test system for identifying if used lithium-ion cells are safe to reuse. We will combine destructive and non-destructive battery testing, operational data from stationary storage and state of the art machine learning methods to classify cells in a safe, fast, scalable, and cost-efficient manner. Hagal’s technology has the ability to both control the electrical load and stream data from individual cells in a battery pack. This means that Hagal products can treat some cells more gently than others in the same pack in order to combine cells with different capacities, chemistries and formats. This simplifies the use of second life cells, because cells with widely different characteristics can be integrated but it is still important to remove and recycle any cells which can contain previously unnoticed defects.

Battery energy storage plays a key role towards a carbon-neutral economy in Europe by enabling the transition to a larger fraction of renewable energy sources. An increasing number of electric vehicles will be retired in the coming years. Extending the useful life of batteries from these EVs can help meet the increasing demand of batteries for energy storage and for use in new applications. At the same time, reuse can significantly lower the yearly averaged carbon footprint of battery cells. There is also a large potential for a greater utilisation of cells which do not meet the producers’ specification, so called B-cells. In this project, Hagal will together with IFE develop and implement a scalable methodology to quickly identify promising battery cells that are suitable for repurposing to alternative applications in a safe and cost-effective manner. Single cell testing differs from the typical approach of testing the entire battery packs, and has the potential to improve performance and safety of reused battery packs as well as the fraction of second-life cells certified for reuse. The methodology will consist of a set of non-destructive tests performed in a test rig, and a cloud side classification model. The system will be scaled for a throughput of 400-4000 cells/day. More exhaustive destructive tests will be used to label non-destructive test data to build and improve on the classification model. A selection of the cells will be put to use in Hagal’s RebelCore systems which allows for a wide variation of battery chemistry form factor and state of health within a single battery pack. Real-time monitoring of the battery cells ensures a feedback loop for continuous improvement of the classification methodology through additional labels on the data as well as providing data to improve models of battery degradation.

Funding scheme:

ENERGIX-Stort program energi